Production of immunoreactive calcitonin by myeloid leukaemia cells

Raised plasma levels of immunoreactive human calcitonin (i-HCT) have been found in patients with chronic granulocytic leukaemia (CGL) in chronic phase and myeloblastic transformation and in patients with acute myeloid leukaemia at presentation and in relapse. In CGL levels were significantly higher in myeloblastic transformation than in the chronic phase. Leukaemia cells were cultured in a short-term liquid culture system in which little cell proliferation occurs and in a two layer blast-cell colony system which permits blast-cell proliferation. i-HCT was identified in supernatant media from cells cultured in both systems but levels were substantially higher in media collected from cells cultured in the latter system. These results suggest that i-HCT is synthesized by proliferating blast cells.